Welcome to nessai’s documentation!

Nessai

nessai (/ˈnɛsi/): Nested Sampling with Artificial Intelligence

nessai is a nested sampling algorithm for Bayesian Inference that incorporates normalising flows. It is designed for applications where the Bayesian likelihood is computationally expensive.

The code is available at: https://github.com/mj-will/nessai.

Contents:

• Installation
• Running the sampler
• Standard sampler configuration
• Importance nested sampler
• Reparameterisations
• Normalising flows configuration
• Parallelisation with nessai
• Gravitational-wave inference
• Further details
• API reference

Examples:

• Simple Gaussian example
• Bilby example

Citing nessai

If you find nessai useful in your work please cite the DOI for this code and our paper:

 @software{nessai,
   author       = {Michael J. Williams},
   title        = {nessai: Nested Sampling with Artificial Intelligence},
   month        = feb,
   year         = 2021,
   publisher    = {Zenodo},
   version      = {latest},
   doi          = {10.5281/zenodo.4550693},
   url          = {https://doi.org/10.5281/zenodo.4550693}
 }

 @article{Williams:2021qyt,
   author = "Williams, Michael J. and Veitch, John and Messenger, Chris",
   title = "{Nested sampling with normalizing flows for gravitational-wave inference}",
   eprint = "2102.11056",
   archivePrefix = "arXiv",
   primaryClass = "gr-qc",
   doi = "10.1103/PhysRevD.103.103006",
   journal = "Phys. Rev. D",
   volume = "103",
   number = "10",
   pages = "103006",
   year = "2021"
}

@article{Williams:2023ppp,
   author = "Williams, Michael J. and Veitch, John and Messenger, Chris",
   title = "{Importance nested sampling with normalising flows}",
   eprint = "2302.08526",
   archivePrefix = "arXiv",
   primaryClass = "astro-ph.IM",
   reportNumber = "LIGO-P2200283",
   month = "2",
   year = "2023"
}